Room-temperature upconverted white light from GdMgB5O10 : Yb3+, Mn2+

Abstract

Room-temperature upconverted white light from GdMgB₅O₁₀ : Yb³⁺, Mn²⁺ has been demonstrated upon 976 nm diode laser excitation, which is low for rare-earth (RE) ion and transition metal (TM) ion codoping systems. The white light emission is composed of two broad bands peaked at 490 and 620 nm, originating from the upconverted emissions of Yb³⁺–Yb³⁺ and Yb³⁺–Mn²⁺ dimer ions, respectively. The cooperative luminescence and cooperative sensitization mechanisms are excluded and exchange interaction models are proposed for these two-photon processes, based on the measured luminescence spectra and crystal structure. The large deviations from two for the plot slopes of the upconversion (UC) intensities as a function of pump power are quantitatively interpreted by a large UC rate for both cases and an additional depletion pathway of relaxation from the upper excited state |²F_7/2,⁴T₁> to the intermediate state |²F_5/2,⁶A₁> for the Yb³⁺–Mn²⁺ dimer according to the exchange interaction model. The color of the UC luminescence can be tuned by varying the content of Yb³⁺ and Mn²⁺, indicating that GdMgB₅O₁₀ : Yb³⁺, Mn²⁺ would be a potential candidate for lighting and displays.